MVVM:如何将参数传递给ViewModel的构造函数 [英] MVVM : how to pass parameter to ViewModel's constructor

问题描述

我正在使用L. Bugnion的MVVM Light Framework.
将参数(例如客户的ID)传递给ViewModel的构造函数的推荐方法有哪些?

I'm using L. Bugnion's MVVM Light Framework.
What are some of the recommended approaches to pass parameters such as Customer's ID to ViewModel's constructor?

我为每个ViewModel需要的参数不是在模型之间共享的.这是每个viewmodel实例唯一的东西.

The parameter I need for each ViewModel is not something that is shared across models. it is something unique to each viewmodel instance.

推荐答案

//Create a container class to pass via messenger service
    public class CarSelectedArgs
    {
      #region Declarations

      public Car Car { get; set; }

      #endregion

      #region Constructor

      public CarSelectedArgs(Car car)
      {
        Car = car;
      }

      #endregion
    }


    //example of view model sending message.
    public class SendingViewModel : ViewModelBase
    {
      private Car _car;
      public Car SelectedCar
      {
        get { return _car; }
        set
        {
          _car = value;
          if (value != null)
          {
            //messenger will notify all classes that have registered for a message of this type
            Messenger.Default.Send(new CarSelectedArgs(value));
          }
        }
      }
    }


    //Example of ViewModel registering to recieve a message
    public class SampleViewModel : ViewModelBase
    {
      #region Constructor

      public SampleViewModel()
      {
        Messenger.Default.Register<CarSelectedArgs>(this, OnCarSelected);
      }
      #endregion

      #region LocalMethods

      void OnCarSelected(CarSelectedArgs e)
      {

        var NewCar = e.Car;
      }

      #endregion
    }

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